It is well known that apertures can be formed in metal stock and similar materials by the use of presses and dies. However, the use of dies is relatively expensive and really only practical for comparatively long production runs. Of course, apertures can also be formed in such materials by drilling, but drilling requires a significant amount of energy and is time consuming. Of the other various methods of forming apertures in relatively thin metal stock, the most practical is that of piercing the stock with a punch. Piercing possesses distinct advantages over the other methods in that it is fast, inexpensive and requires a minimum expenditure of energy.
In the past there have been various attempts made to develop punch mechanisms which could be employed with conventional presses to convert the normal downward vertical stroke of the press ram into a nonvertical, angled or horizontal stock-piercing stroke. Representative of such devices is that shown in U.S. Pat. No. 3,256,730. Although such units are commercially available they are not completely satisfactory in part, because they do not have adequate lubrication systems to reduce frictional wear and to extend their useful life.